Resumo

Behavior is an evolutionary product and, at least, some disorders may affect different species throught homologous etiological mechanisms. The present study evaluated the compulsive nature of the locomotor hyperactivity observed in rats with electrolytic lesion of the median raphe nucleus, a possible behavioral inhibition system postulated by the ethologists. The number of crossings of the median line of a wiremesh cage was counted during 10 minutes in lesioned (n=6) and controls (n=7) rats (baseline period). They were submitted during 30s to footshocks and crossings were counted again. The number of crossings was higher in lesioned animals and did not reduce significantly after the aversive stimulation. Control animals showed long lasting behavioral freezing after shocks that resulted in significantly lower rates of crossings. It is concluded that such lesioned rats may be a valuable paradigm for studies on repetitive behavior disorders.